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Although this power supply design is specific to the Intelligent Power Modules (IPM) VFD drives, high voltage boost converters, high voltage battery chargers, etc, the concept and circuit design may be used for any power supply that requires a high voltage output of up to 800V DC and 4 A. Since it is an unregulated power supply the output will depend on AC input voltage. The circuitry includes a passive EMI filter consisting of elements C8, C9, C4, T1, and L1. Bridge rectifier D1, R1 for inrush current protection, and a relay RL1 for soft powering up and reducing conduction losses in steady-state. 4 x electrolytic capacitors C2, C3, C6, C7 are used for buffering the rectified DC bus voltage, bleeding resistors R1, and R2 provided to discharge the DC bus capacitor after power off. It is advisable to use a heatsink for the bridge rectifier. Inrush current circuit requires 12-15V DC @ 80mA. Choose appropriate fuse as per current requirement. The relay takes care of the inrush current. It is important to switch ON the 12V-15V DC and 3phase power same time.

We have tested this power supply with Input 3 Phase 430V AC, Output 620V DC, Continued Current 5A, but it is advisable to use it at max 3A continued current.”

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